Recently, semiconductor integrated circuit devices are required to operate at a high speed. The speedup of operation is mainly driven by the miniaturization of semiconductor devices such as transistors or the like, the reduction in wiring resistance, the reduction in dielectric constant of interlayer insulating films, and the like. However, there are limitations in the advancement of progress utilizing these techniques. Therefore, in order to make further advancements, silicon germanium (hereinafter also referred to as SiGe) or germanium (hereinafter also referred to as Ge), which is a semiconductor material having a higher carrier mobility, draws attention instead of silicon (hereinafter also referred to as Si), which has been used as a semiconductor material.
When Ge or SiGe is applied to a semiconductor device, a technique of etching Ge or SiGe with high selectivity is required. For example, a technique of selectively etching SiGe with respect to Si using a F2 gas or both a F2 gas and an NH3 gas has been used.
However, in the related art, only SiGe etching is performed, and Ge is not etched. For dry etching of Ge, a halogen gas or a high temperature thermal oxidizing treatment has been used. However, the selectivity thereof to other materials is not sufficient.